The present invention relates to ventilation systems having air filtering and diffusing devices, and more particularly, to air filtering and diffusing ceilings and walls for environmentally controlled rooms.
Various air filtering and distribution structures for use in environmentally controlled rooms are known.
One type of ceiling construction for environmentally controlled rooms is a dropped ceiling formed entirely of filter panels defining a dirty air plenum between it and the ceiling of the room. The filter panels filter the dirty air as it passes from the dirty air plenum into the room, and, of course, since the entire dropped ceiling is formed of filter panels, distributes the air in a more or less uniform manner across the length and breadth of the ceiling for generally vertical flow across the room.
Yet another type of air filtering and distribution structure for a clean room is a wall formed entirely of filter panels having a dirty air plenum between it. The filter panels filter the dirty air as it passes from the dirty air plenum into the room, and, since the entire filter wall is formed of filter panels, distributes the air in a more or less uniform manner across the length and height of the filter wall for generally horizontal flow across the room.
Another type of ceiling construction is a dropped ceiling formed entirely of air deflecting panels which ceiling defines a conditioned air plenum between it and the ceiling of the room. The plenum receives temperature and humidity conditioned air through an air supply vent and deflecting elements formed in the dropped ceiling panels distribute the temperature and humidity conditioned air across the length and breadth of the ceiling as it passes from the plenum to the room.
In various industries, the parameters for an environmentally controlled room vary greatly depending upon the function to which the room will be put. In the pharmaceutical and aerospace fields, for example, the standards for air cleanliness are rigid. In other industries, for example, the precision gauging industries, the prime environmental consideration in an environmentally controlled room is uniform temperature and humidity control, with cleanliness being a parameter of secondary importance, the filter associated with a temperature and humidity conditioning apparatus being adequate to clean the air before it is introduced into the room.
One consideration which is common to every industry, however, is cost. Environmentally controlled rooms are very expensive and are usually considered capital expenditure items. An environmentally controlled room which cleans the air to a greater degree than is needed for the type of work done in the room is "over engineered" for the application and is therefore extremely wasteful.
The above-described environmentally controlled room air filtering and distribution structures represent, so to speak, opposite ends of the spectrum as it relates to cleaning the air admitted to an environmentally controlled room. The first and second mentioned constructions having a dropped ceiling or wall, respectively, formed entirely of filter panels represent that end of the spectrum requiring essentially absolute clean air while the third mentioned ceiling construction represents the other end of the spectrum requiring only a minimum degree of air cleanliness.